Recent work demonstrates that transformed cells can produce mitogenic agents capable of stimulating fibroblast proliferation. Also, work with normal cells and tissue has recently demonstrated that macrophages and platelets contain and elaborate potent mitogens capable of stimulating fibroblast proliferation. Reticulin fibrosis, collagen formation, and fibroblast proliferation are seen in conjunction with many human malignancies. Most notable of these is Nodular Sclerosing Hodgkin's disease in which thick fibroblast hyperplasia and collagen bands frequently compose the bulk of the neoplasm. There is considerable evidence that the Hodgkin's cell (Reed-Sternberg cell and mononuclear variants) is a malignant macrophage. It is hypothesized that during malignant transformation, the Hodgkin's cell acquires or greatly increases the ability to produce a growth factor(s) which is(are) responsible for fibroblast hyperplasia and, consequently, thick collagen band formation. The experiment outlined here is designed to test this hypothesis and confirm pilot studies utilizing short term cultures of purified Hodgkin's cells from which conditioned medium will be obtained. Hodgkin's cell cultures will be initiated in a thin layer of plasma. The growth of resting BALB/c 3T3 cells, human diploid fibroblasts, and human embryonic fibroblasts in this conditioned medium will be analyzed by measuring increase in cell number and incorporation of tritiated thymidine. Control growth factors will be calf serum and Fibroblast Growth Factor (FGF). Analysis of the cell of origin will be completed. Chemical extraction and partial purification of Hodgkin's Disease Growth Factor (HDGF) will be performed using tissue involved by nodular sclerosing Hodgkin's disease. Preliminary evidence of circulating HDGF in patients with active disease will be confirmed. The activity of HDGF and FGF will be compared against fibroblasts grown on plastic and on an extracellular matrix produced by bovine corneal endothelial cells.